The invention relates to a powder supply system, a spray system and an apparatus for the surface treatment of a workpiece in accordance with the pre-characterising part of the independent claim in the respective category.
Powder processing apparatuses of the most diverse kinds, which have to be supplied in the operating state with powdery materials such as spray powders or minerals, such as sand and granulates for example, which can consist of the most diverse materials, include, as a rule, a powder supply system, which essentially consists of a powder feed system using the powder from a storage container, in which a certain amount of the required powder can be stored as a reserve, and which can be fed to the powder processing apparatus.
In industrial practice the previously mentioned powder processing apparatus can, for example, be thermal spraying apparatus such as plasma pistols, cold gas spraying systems, or the diverse well-known flame spraying and arc spraying systems (in which, for example, in addition to a spraying wire, powder is also processed) or other spraying systems processing powder, with which, for example, the surfaces of workpieces can be upgraded. An example of other powder processing apparatuses is apparatus for the surface treatment of workpieces, for example for the abrasive, roughening or polishing treatment of a surface of a workpiece by means of a blasting material, for example by means of minerals such as sand, fine dust or of a metallic, ceramic or synthetic blasting material.
The problem with all of these powder processing apparatuses named as an example and known from the prior art is that they have conventional powder feed systems, the storage containers of which are of limited capacity for the corresponding powder or blasting material. In the case of thermal spraying systems this capacity is, as a rule, a maximum volume of 7 liters. This is a considerable obstacle for mass production in particular when parts are to be manufactured in very large numbers in series, for example have to be provided with a thermally sprayed layer, or if the surfaces of workpieces have to be treated with a blasting material by means of blasting.
In mass production the processes, for example the coating of workpieces, have to be halted at regular intervals relatively often in order to reload the storage containers. This results in considerable time delays, and moreover can only be achieved with difficulty.
Moreover, the quality of the process is not completely independent of the filling level of the storage container. Thus it can be advantageous during thermal spraying, depending on the spraying method, and/or on the spraying material and/or on the quality required of the layer to be sprayed, that the filling level in the storage container only changes between a predetermined maximum and a minimum value, since the concrete filling state also has an effect on the powder supply rate, so that a higher and/or a lower filling level can have a negative effect on the quality of a layer to be sprayed.